Well, according to Hayato in Getter Go volume 5, "It ended the reign of the dinosaurs," "... it was responsible for accelerating our evolution," and, "It's also a clean and infinite energy..." We can take as fact, therefore, that Getter Rays kill dinosaurs for some reason, accelerate the evolution of certain creatures but not others, and is an infinite energy source that produces no pollution. I've heard that Getter Rays kill dinosaurs because it hyper evolves them until they disintegrate, but it makes them look more like they melt from something like Breast Fire. It's probably also likely that different continuities (classic anime, Armaggedon, Shin vs. Neo, Go, New, and of course manga) have different rules for how Getter Rays work.

I think this was in the end of Go: Shin Getter is used as the avatar for Getter Energy, and they speak to Go directly telling him that natural forces have wills of their own, Getter Rays being the will of evolution itself.

AnonyGuest

Subject: Re: Getter rays 3/7/2012, 12:15 am

Well, we do know that it's the embodiment of life and has its own will and part in the "plan". The moral of the end of Getter Robo Go seemed to be that life can aquire new heights at times of hardship. So my idea is that everything it does serves that. Getter rays came to Earth to force the creatures here to adapt to it and evolve, including the dinosaurs.Getter Emperor fucking shit up was also because of that, it was just a normal war for dominance, and it stands to reason that there are losers. It intervened when the Andromeda Flow Country tried to destroy Earth, because using time travel to destroy a species when it has no way of fighting back is cheating.